1 /* $NetBSD: kern_ras.c,v 1.34 2008/10/15 06:51:20 wrstuden Exp $ */ 2 3 /*- 4 * Copyright (c) 2002, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Gregory McGarry, and by Andrew Doran. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __KERNEL_RCSID(0, "$NetBSD: kern_ras.c,v 1.34 2008/10/15 06:51:20 wrstuden Exp $"); 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/kmem.h> 39 #include <sys/proc.h> 40 #include <sys/ras.h> 41 #include <sys/sa.h> 42 #include <sys/savar.h> 43 #include <sys/xcall.h> 44 #include <sys/syscallargs.h> 45 46 #include <uvm/uvm_extern.h> 47 48 #define MAX_RAS_PER_PROC 16 49 50 u_int ras_per_proc = MAX_RAS_PER_PROC; 51 52 #ifdef DEBUG 53 int ras_debug = 0; 54 #define DPRINTF(x) if (ras_debug) printf x 55 #else 56 #define DPRINTF(x) /* nothing */ 57 #endif 58 59 /* 60 * Force all CPUs through cpu_switchto(), waiting until complete. 61 * Context switching will drain the write buffer on the calling 62 * CPU. 63 */ 64 static void 65 ras_sync(void) 66 { 67 68 /* No need to sync if exiting or single threaded. */ 69 if (curproc->p_nlwps > 1 && ncpu > 1) { 70 #ifdef NO_SOFTWARE_PATENTS 71 uint64_t where; 72 where = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL); 73 xc_wait(where); 74 #else 75 /* 76 * Assumptions: 77 * 78 * o preemption is disabled by the thread in 79 * ras_lookup(). 80 * o proc::p_raslist is only inspected with 81 * preemption disabled. 82 * o ras_lookup() plus loads reordered in advance 83 * will take no longer than 1/8s to complete. 84 */ 85 const int delta = hz >> 3; 86 int target = hardclock_ticks + delta; 87 do { 88 kpause("ras", false, delta, NULL); 89 } while (hardclock_ticks < target); 90 #endif 91 } 92 } 93 94 /* 95 * Check the specified address to see if it is within the 96 * sequence. If it is found, we return the restart address, 97 * otherwise we return -1. If we do perform a restart, we 98 * mark the sequence as hit. 99 * 100 * No locking required: we disable preemption and ras_sync() 101 * guarantees that individual entries are valid while we still 102 * have visibility of them. 103 */ 104 void * 105 ras_lookup(struct proc *p, void *addr) 106 { 107 struct ras *rp; 108 void *startaddr; 109 lwp_t *l; 110 111 startaddr = (void *)-1; 112 l = curlwp; 113 114 KPREEMPT_DISABLE(l); 115 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 116 if (addr > rp->ras_startaddr && addr < rp->ras_endaddr) { 117 startaddr = rp->ras_startaddr; 118 DPRINTF(("RAS hit: p=%p %p\n", p, addr)); 119 break; 120 } 121 } 122 KPREEMPT_ENABLE(l); 123 124 return startaddr; 125 } 126 127 /* 128 * During a fork, we copy all of the sequences from parent p1 to 129 * the child p2. 130 * 131 * No locking required as the parent must be paused. 132 */ 133 int 134 ras_fork(struct proc *p1, struct proc *p2) 135 { 136 struct ras *rp, *nrp; 137 138 for (rp = p1->p_raslist; rp != NULL; rp = rp->ras_next) { 139 nrp = kmem_alloc(sizeof(*nrp), KM_SLEEP); 140 nrp->ras_startaddr = rp->ras_startaddr; 141 nrp->ras_endaddr = rp->ras_endaddr; 142 nrp->ras_next = p2->p_raslist; 143 p2->p_raslist = nrp; 144 } 145 146 DPRINTF(("ras_fork: p1=%p, p2=%p\n", p1, p2)); 147 148 return 0; 149 } 150 151 /* 152 * Nuke all sequences for this process. 153 */ 154 int 155 ras_purgeall(void) 156 { 157 struct ras *rp, *nrp; 158 proc_t *p; 159 160 p = curproc; 161 162 if (p->p_raslist == NULL) 163 return 0; 164 165 mutex_enter(&p->p_auxlock); 166 if ((rp = p->p_raslist) != NULL) { 167 p->p_raslist = NULL; 168 ras_sync(); 169 for(; rp != NULL; rp = nrp) { 170 nrp = rp->ras_next; 171 kmem_free(rp, sizeof(*rp)); 172 } 173 } 174 mutex_exit(&p->p_auxlock); 175 176 return 0; 177 } 178 179 #if defined(__HAVE_RAS) 180 181 /* 182 * Install the new sequence. If it already exists, return 183 * an error. 184 */ 185 static int 186 ras_install(void *addr, size_t len) 187 { 188 struct ras *rp; 189 struct ras *newrp; 190 void *endaddr; 191 int nras, error; 192 proc_t *p; 193 194 endaddr = (char *)addr + len; 195 196 if (addr < (void *)VM_MIN_ADDRESS || 197 endaddr > (void *)VM_MAXUSER_ADDRESS) 198 return (EINVAL); 199 200 if (len <= 0) 201 return (EINVAL); 202 203 newrp = kmem_alloc(sizeof(*newrp), KM_SLEEP); 204 newrp->ras_startaddr = addr; 205 newrp->ras_endaddr = endaddr; 206 error = 0; 207 nras = 0; 208 p = curproc; 209 210 mutex_enter(&p->p_auxlock); 211 for (rp = p->p_raslist; rp != NULL; rp = rp->ras_next) { 212 if (++nras >= ras_per_proc) { 213 error = EINVAL; 214 break; 215 } 216 if (addr < rp->ras_endaddr && endaddr > rp->ras_startaddr) { 217 error = EEXIST; 218 break; 219 } 220 } 221 if (rp == NULL) { 222 newrp->ras_next = p->p_raslist; 223 p->p_raslist = newrp; 224 ras_sync(); 225 mutex_exit(&p->p_auxlock); 226 } else { 227 mutex_exit(&p->p_auxlock); 228 kmem_free(newrp, sizeof(*newrp)); 229 } 230 231 return error; 232 } 233 234 /* 235 * Nuke the specified sequence. Both address and len must 236 * match, otherwise we return an error. 237 */ 238 static int 239 ras_purge(void *addr, size_t len) 240 { 241 struct ras *rp, **link; 242 void *endaddr; 243 proc_t *p; 244 245 endaddr = (char *)addr + len; 246 p = curproc; 247 248 mutex_enter(&p->p_auxlock); 249 link = &p->p_raslist; 250 for (rp = *link; rp != NULL; link = &rp->ras_next, rp = *link) { 251 if (addr == rp->ras_startaddr && endaddr == rp->ras_endaddr) 252 break; 253 } 254 if (rp != NULL) { 255 *link = rp->ras_next; 256 ras_sync(); 257 mutex_exit(&p->p_auxlock); 258 kmem_free(rp, sizeof(*rp)); 259 return 0; 260 } else { 261 mutex_exit(&p->p_auxlock); 262 return ESRCH; 263 } 264 } 265 266 #endif /* defined(__HAVE_RAS) */ 267 268 /*ARGSUSED*/ 269 int 270 sys_rasctl(struct lwp *l, const struct sys_rasctl_args *uap, register_t *retval) 271 { 272 273 #if defined(__HAVE_RAS) 274 /* { 275 syscallarg(void *) addr; 276 syscallarg(size_t) len; 277 syscallarg(int) op; 278 } */ 279 void *addr; 280 size_t len; 281 int op; 282 int error; 283 284 /* 285 * first, extract syscall args from the uap. 286 */ 287 288 addr = (void *)SCARG(uap, addr); 289 len = (size_t)SCARG(uap, len); 290 op = SCARG(uap, op); 291 292 DPRINTF(("sys_rasctl: p=%p addr=%p, len=%ld, op=0x%x\n", 293 curproc, addr, (long)len, op)); 294 295 switch (op) { 296 case RAS_INSTALL: 297 error = ras_install(addr, len); 298 break; 299 case RAS_PURGE: 300 error = ras_purge(addr, len); 301 break; 302 case RAS_PURGE_ALL: 303 error = ras_purgeall(); 304 break; 305 default: 306 error = EINVAL; 307 break; 308 } 309 310 return (error); 311 312 #else 313 314 return (EOPNOTSUPP); 315 316 #endif 317 318 } 319